SURVIVAL OF SKIN HOMOGRAFTS IN RADIATION CHIMERAS

Homologous rabbit radiation chimeras accept skin homografts from donors unrelated to both recipient and marrow donor if placed immediately after irradiation; they reject in a normal way skin homografts placed six months later. Secondary transplantation immunity in homologous rabbit radiation chimeras is maintained, although delayed when either the recipient or the marrow donor is pre- sensitized. Irradiated rabbits protected with autologous marrow reject skin homografts after considerable delay. C57L mouse isologous radiation chimeras retain for a considerable time skin from C57BL/6 mice (same H-2 locus) but reject skin from C3H (different H-2 locus) if these grafts are placed immediately after irradiation. The prolongation of the C57BL/6 skin grafts is less marked if the grafts are applied 17 days later or if 400 r is given without marrow support. The above findings might possibibly be interpreted as a result of acquired tolerance by the donober marrrow. As a consequence, secondary disease does no not result from transplantation immunity, but rather from circulating-type antibodies produced by the grafted marrow. (auth)